Low-grade fibromyxoid sarcoma

No evidence of fracture. No loosening of femoral stem.

Round soft-tissue lesion, hypodense to muscle, measuring 5.3 x 4.3 x 6.3 cm (LL x AP x CC), ballooning into the vastus intermedius from the anterior femoral cortex at the distal end of the femoral stem, eroding through the entire thickness of the cortex.

Total body ^99mTc-MDP triphasic bone scintigraphy with pelvic SPECT:

• high-intensity horizontal uptake focus in the sacrum, compatible with fracture - osteoporotic insufficiency fracture? trauma?
• moderately increased uptake adjacent to the right hip prosthesis under the trochanter, with elevated early phase perfusion - clinical correlation required for ruling out infection
• increased irregular uptake in the shoulders and along the spine, degenerative arthritic changes in the knees

Mass measuring 7.3 x 4.5 x 4.9 cm with mixed echotexture in the front of the right hip, mostly hypoechoic with echogenic areas. The mass abuts the femoral bone.

Under local anesthesia with 7 ml of lidocaine 1%, four aspirations from the mass substance with 14G-18G needles. Transparent, whitish gelatinous substance received. Part of the material was placed on 8 slides for cytologic evaluation and part was transferred into a sterile stoppered syringe. In addition, two core biopsies were taken from the echogenic material with a Magnum device using a 14G needle. Two good-quality cores of the gelatinous/tissue material were obtained.

Intramedullary fixation in the proximal femoral diaphysis.

At the middle third of the thigh, deep inside the vastus intermedius, there is a lesion displaying a low signal on T1WI and a high signal on T2WI, that undergoes mild heterogeneous contrast enhancement. The lesion measures 4.8 x 4.7 x 8.1 cm (ml x ap x cc). It violates the cortex and reaches the tip of the intramedullary stem. The lesion's characteristics favor a soft-tissue sarcoma.

The neurovascular structures appear normal.